Gene Therapy: Principles, Vectors and Ethics | 基因治疗：原理、载体与伦理

📚 Gene Therapy: Principles, Vectors and Ethics | 基因治疗：原理、载体与伦理

Gene therapy is an experimental technique that uses genes to treat or prevent disease. In A-level biology, it is usually defined as the insertion of a normal allele into the cells of a patient who carries a defective allele, with the aim of restoring a functional protein. Although the concept is simple, delivering a gene safely into the correct cells and maintaining its expression remain major challenges.

基因治疗是一种利用基因来治疗或预防疾病的实验性技术。在 A-level 生物中，它通常被定义为将正常等位基因导入携带缺陷等位基因的患者细胞中，以恢复功能性蛋白质。尽管概念简单，但将基因安全地递送到正确细胞并维持其表达仍然是主要挑战。

Gene therapy is not yet a routine treatment for most genetic disorders, but it has produced clear successes in a small number of diseases. It is an applied genetics topic that brings together knowledge of DNA, protein synthesis, mutation, enzymes, cell division and the immune system.

基因治疗尚未成为大多数遗传病的常规治疗方法，但已在少数疾病中取得了明确成功。这是一个应用遗传学主题，将 DNA、蛋白质合成、突变、酶、细胞分裂和免疫系统等知识结合在一起。

1. What is gene therapy? | 什么是基因治疗？

At the syllabus level, gene therapy aims to correct loss-of-function mutations by adding a working copy of the gene. It can also be used to silence a harmful dominant allele or introduce a new function into cells, for example in cancer immunotherapy. Most current gene therapy trials target somatic cells, so the correction is not inherited by the patient’s offspring.

在考纲层面，基因治疗旨在通过添加一个可工作的基因拷贝来纠正功能丧失型突变。它也可用于沉默有害的显性等位基因，或向细胞引入新功能，例如在癌症免疫治疗中。目前大多数基因治疗试验以体细胞为靶标，因此纠正不会遗传给患者的后代。

A common misconception is that gene therapy always replaces a faulty gene. In fact, many treatments use gene addition: the defective allele remains present, but the added functional allele produces enough protein to improve the phenotype. Gene editing tools such as CRISPR-Cas9 may eventually allow precise correction, but they are still being tested for safety.

一个常见的误解是基因治疗总是替换有缺陷的基因。事实上，许多治疗采用基因添加：缺陷等位基因仍然存在，但添加的功能性等位基因产生足够的蛋白质来改善表型。CRISPR-Cas9 等基因编辑工具最终可能实现精确修复，但其安全性仍在测试中。

For a gene to be expressed, it must enter the nucleus, be transcribed into mRNA and then be translated into protein. Therefore gene therapy is only useful when the disease mechanism is understood and when the target cells are accessible and long-lived enough to produce the therapeutic protein.

基因要表达，必须进入细胞核，转录为 mRNA，然后翻译成蛋白质。因此，只有当疾病机制明确，并且靶细胞可及且存活时间足够长以产生治疗性蛋白质时，基因治疗才有用。

2. Somatic vs germline gene therapy | 体细胞与生殖细胞基因治疗

Somatic gene therapy modifies body cells such as bone marrow stem cells, lung epithelial cells or retinal cells. The change affects only the treated individual and is not passed to the next generation. This is the only form of

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